Process for producing foods having good keeping qualities and food keeping agents

ABSTRACT

The present invention provides a food preservative which contains an antibacterial substance having a high safety and which enhances the preservability of a food without exerting an adverse influence to the taste and flavor of the food; and a method for preserving a food. 
     The following substances are used alone or in combination for a food additive: 1,5-D-anhydrofructose, and one or two or more of substances having an antibacterial activity and each capable of being used as a food additive such as amino acids such as glycine, alanine and the like; glycerin lower fatty acid esters; sugar esters; salts of vitamin B1; polyphosphates; ethanol; basic proteins and peptides such as protamine or the like; antibacterial extract from licorice; extract from red pepper; extract from hop; extract from yucca; extract from moso bamboo (thick-stemmed bamboo); extract from grape fruit seed; extract from wasabi (Japanese horseradish) or mustard; organic acids such as acetic acid or the like and the salts thereof; sorbic acid, benzoic acid and the salts and esters thereof; propionic acid and the salt thereof; chitosan and bacterium DNA.

TECHNICAL FIELD

The present invention relates to a process for producing a food havingexcellent preservability, and a food preservative.

BACKGROUND ART

The storage and preservation of foods in stores and homes in the courseof distribution of foods are themes required to be always solved.Various physical and chemical processes have been conceived as measuresfor such themes. Examples of the measures taken hitherto are freezing,refrigeration, drying, preservation in salt, preservation in sugar, heatsterilization, heat pasteurization (bottling and canning), heatingpackages, gas substitution of the inside of the packages, and use of achemical preservative such as benzoic acid, sorbic acid and the like.

The safety is first of all required at all times, but in recent years,particularly, the interest in health and foods is heightened and inaddition, the interest in natural foods or foods close to natural foodsis growing. Such a tendency to the foods in the recent years exerts aremarkable influence to food-preserving processes.

One problem associated with the current foods is that a nationalboundary for foods has been eliminated, and that food materials or foodsthemselves have been imported from all places in all over the world.This means that various microorganisms adhering to or polluting foodshave been widely brought to food markets along with the foods, resultingin indication of risks of the food poisoning caused by many newfood-poisoning bacteria, e.g., E. coli O-157:H7, several salmonellae,and A-type or B-type botulinus bacilli which have been so far lessdetected in Japan.

Further, a wide variety of cooked foods have increased in recent years.For example, so-called subsidiary foods such as salads, sandwiches,fried eggs, chicken nugget, custard creams, boiled foods, fried foods,pickles or pickled vegetables and the like have been placed on themarkets, while being demanded for the assurance of the stability againstmicroorganisms for a given period in its own way.

It is an intention for the health to reduce the concentration of salt inall preservable foods. For example, the concentration equal to or higherthan 10% of salt in salted guts of cuttlefish has been reduced to 4 to5%; the concentration of salt in pickled vegetables in a range of 12 to13% has been reduced to 4 to 6%; and the concentration of salt in asoybean paste, i.e., miso on the order of 13% has been reduced to 4 to8%. This means that the stability of the foods against microorganismshas been reduced remarkably. The foods have been liable to be not merelyputrefied, but also the safety against various food poisoning bacteriahas been reduced.

In such a situation, the basic measures for food-preservation takenusually are as follows, for example: (1) to clean the food producingenvironment, (2) to reduce the pollution of foods by microorganisms to alevel as low as possible at steps of producing and packing the foods,(3) to use food materials having a degree as small as possible ofpollution by microorganisms, (4) to control a course from a producingstep to a packing step to a temperature as low as possible, and (5) topreserve food products at a low temperature. However, it is extremelydifficult to reduce the number of microorganisms in raw food materialscompletely to zero, and even when foods have been put at a lowtemperature, some of bacteria proliferate well even at the lowtemperature and hence, they may grow with the passage of time to putrefythe foods in some cases.

On the other hand, it is a process known from old times to enhance thepreservability of foods by heating the foods. However, to carry out theperfect sterilization, a severe heating condition must be set and insuch a case, the value of food itself is reduced due to the degradationof nutritious components in the food and to the loss in taste inherentin the food. For this reason, in practice, a heating condition moderateto a certain extent is set and hence, a perfect sterilization cannot beachieved. For example, fabricated foods having increased in recent yearssuffer from a problem of the deterioration caused by heat-resistantbacteria such as Bacillus remaining in a food after fabrication underheating of the food, and sealed foods such as a canned coffee alsosuffer from a problem of the deterioration caused by flat-sour spoilagebacteria. Further, a problem of food poisoning due to a secondarypollution arises frequently.

To solve these problems, a variety of techniques for enhancing thepreserving food technique have been developed, and the addition of apreservative is one of such techniques. In general, the preservativesare broadly classified into a synthesized preservative designated in theFood Hygiene Law, another food additive having a food preservationeffect and a naturally occurring material. However, there is arestriction on use of the synthesized preservative, and some ofcustomers have apprehensions about the safety, particularly, aninfluence on a human body and hence, there is a tendency in recent yearsto keep a synthesized preservative from being added. Consequently, theutilization of an antibacterial substance excellent in safety andsubstituted for the synthesized preservative has been studied.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide process forproducing a food having excellent preservability, retaining quality byusing an antibacterial substance excellent in safety.

It is another object of the present invention to provide a foodpreservative which contains an antibacterial substance excellent insafety, can enhance the preservability of a wide variety of foods andmoreover, does not drop the quality, and to provide a process forpreserving foods.

The further objects and advantages of the present invention will becomeapparent from the following description.

According to the present invention, the above objects and advantages areachieved, first, by a process for producing a food having excellentpreservability, which comprises the step of heating a food, while adding1,5-D-anhydrofructose, or the steps of adding 1,5-D-anhydrofructose to afood and then heating the food (this process may be referred to as afirst process of the present invention hereinafter).

According to the present invention, the above objects and advantages areachieved, secondly, by a process for producing a food having excellentpreservability, which comprises the step of adding 1,5-D-anhydrofructosepreviously subjected to a heat treatment to a food (this process may bereferred to as a second process of the present invention hereinafter).

According to the present invention, the above objects and advantages areachieved, thirdly, by a food preservative containing

(A) one or both of 1,5-D-anhydrofructose and 1,5-D-anhydrofructosepreviously subjected to a heat treatment, and

(B) a substance capable of being used as a food additive and having anantibacterial activity.

According to the present invention, the above objects and advantages areachieved, fourthly, by a process for producing a food having excellentpreservability, which comprises the step of adding the above-describedfood preservative to a food (this process may be referred to as a thirdprocess of the present invention).

According to the present invention, the above objects and advantages areachieved, fifthly, by a method for preserving a food, which comprisesadding the above-described food preservative to a food and preservingthe obtained food (this process may be referred to as a fourth processof the present invention).

The further objects and advantages of the present invention will becomeapparent from the following description.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a curve indicating the number of Pseudomonas aeruginosa IFO12680 killed by heating.

FIG. 2 is a curve indicating the number of which Salmonella typhimuriumIFO 12529 killed by heating.

FIG. 3 is a graph showing the number of Bacillus. subtillis IAM 1249living in a noodle soup under preservation.

FIG. 4 is a graph showing the number of Escherichia coli NRIC 1023living in a noodle soup under preservation.

PRACTICAL EMBODIMENT OF THE INVENMTION

1,5-D-anhydrofructose which is an antibacterial substance used in thepresent invention can be produced from starch or a decomposition productof starch, as a substrate, by the action of an enzyme, α-1,4-glucanlyase (which will be simply referred to as lyase hereinafter) existingin tissues of a plant such as red alga or in a microorganism such asBasidiomycetes. This 1,5-D-anhydrofructose is a compound having astructure of glucose dehydrated.

Various chemical substances showing an antibacterial effect have beenconventionally synthesized and utilized, but 1,5-D-anhydrofructose canbe produced from starch which is a polysaccharide, by the action of anenzyme and hence, 1,5-D-anhydrofructose is safe for use in a food. Inaddition, 1,5-D-anhydrofructose has a proliferation-inhibiting effectbroadly against gram-positive bacteria, is also effective in particularagainst Bacillus subtillis, Bacillus cereus and Lactobacillus casei andthe like, which cause the pollution at a high frequency. Bacillussubtillis and Bacillus cereus are heat-resistant spore-forming bacteriaremaining even after a usual heat treatment of fabricated foods, andLactobacillus casei, too, cause the deterioration of various foods.Antibacterial substances safe and effective for these bacteria are fewand hence, 1,5-D-anhydrofructose is of much value as an antibacterialsubstance having a high safety.

Firstly, the first process of the present invention will be describedbelow.

Though 1,5-D-anhydrofructose has been recognized to exhibitproliferation-inhibiting effect at a concentration of 1% or less againstmany bacteria, in the first process of the present invention, it ispreferable that 1,5-D-anhydrofructose is added in an amount of 0.01 to10% by weight to a food. When the amount of 1,5-D-anhydrofructose islower than 0.01% by weight, the antibacterial effect is insufficient,while when the amount exceeds 10% by weight, the resulting food is feltbitter. A more preferable amount of 1,5-D-anhydrofructose added is in arange of 0.1 to 5% by weight.

In the first process of the present invention, the food is heated whileadding 1,5-D-anhydrofructose to the food, or after addition of1,5-D-anhydrofructose to the food. The antibacterial effect of1,5-D-anhydrofructose is increased by the heating and as compared with acase where the food is not heated, the antibacterial effect is exhibitedeven in addition of 1,5-D-anhydrofructose at a lower concentration tothe food, to make the food added with 1,5-D-anhydrofructose difficult toputrefy. The 1,5-D-anhydrofructose originally has an antibacterial powerextremely weak against gram-negative bacteria, but exhibits a strongantibacterial power even against gram-negative bacteria by being heated.

FIGS. 1 and 2 show curves each indicating the number of gram-negativebacteria killed in a soybean-casein digest broth medium (pH of 5.5) byheating. More specifically FIG. 1 shows data concerning Pseudomonaswhich is typical gram-negative bacteria. FIG. 1 shows that when1,5-D-anhydrofructose existed in an amount of 1% in the food, the numberof bacteria remaining alive as a result of heating of the food at 55° C.for ten minutes was one tenth of that in the control.

FIG. 2 shows data concerning Salmonella bacteria which are typicalgram-negative bacteria causing food poisoning of the same gram-negativebacteria, when 1,5-D-anhydrofructose was added in an amount of 1% to thefood. FIG. 2 shows that when the food containing 1,5-D-anhydrofructoseadded thereto was heated at 60° C. for 10 minutes, the number ofbacteria remaining alive was one hundredth or less of that in thecontrol.

As shown in FIGS. 3 and 4, it has been found that when1,5-D-anhydrofructose is added to a food and the food is then heated, aheat sterilizing effect on both of gram-positive bacteria (Bacillussubtillis IAM 1249 in FIG. 3) and gram-negative bacteria (Escherichiacoli NRIC 1023 in FIG. 4) is promoted and further, the subsequentproliferation of the bacteria is inhibited. This will be described indetail later in Test Example 2.

The term “heating of food” used in the first process of the presentinvention means the heating of foods for cooking the foods into ediblefoods by steaming, boiling, roasting, broiling and frying, as well asthe heating of foods for sterilization at a high temperature and under ahigh pressure, for example, for canning, bottling and retort-pouchingand further includes the reheating of foods for sterilization afterbeing packaged.

In a food produced through a heating process, the developing of anantibacterial power of 1,5-D-anhydrofructose is extremely high, and thepreservability of the food is remarkably enhanced, as compared with thedeveloping of an antibacterial power of 1,5-D-anhydrofructose in a foodproduced without being subjected to a heating process. Therefore, toeffectively exhibit the antibacterial power of 1,5-D-anhydrofructose,the heating process is essential.

The foods to be used in the first process of the present invention arenot particularly limited, if they are foods produced through the heatingprocess for cooking, sterilization and the like. For example, theyinclude boiled rice, rice cakes, boiled noodles, breads, bean jams,Japanese-style confections and cakes, flour pastes, aquatic andlivestock paste products, fried eggs, custard puddings, noodle soups,bastes, sauces, tea beverages such as canned coffee, canned red tea,canned green tea, water-boiled vegetables, various retort-pouched roux,bottled near-water, fruit drinks, subsidiary foods such as boiled beans,boiled fishes, fried foods, foods boiled down in soy, pickles or pickledvegetables and the like.

In the first process of the present invention, 1,5-D-anhydrofructose isfirst added to a food. The adding method is not particularly limited,and with a various foods, an optimal adding method can be employed at anoptimal adding time before heating of the food. For example,1,5-D-anhydrofructose may be dissolved in cooking water or the like andadded to the food when the food is cooked. To produce noodles or breads,1,5-D-anhydrofructose may be mixed into a material flour, and theresulting material may be subjected to a treatment for forming a noodleor a bread. Or, a food may be immersed into an aqueous solution of1,5-D-anhydrofructose, or an aqueous solution of 1,5-D-anhydrofructosemay be sprayed onto a food.

Then, when such a food containing 1,5-D-anhydrofructose is thensubjected to a heat treatment for cooking or sterilization, a foodexcellent in preservability is obtained. The appropriate heatingconditions vary depending on the type of food, but may be a temperatureof 50 to 250° C. and a time of 1 second to 300 minutes. Withretort-pouched foods, the preferred conditions vary depending on thetype of food, but may be a temperature of about 120 to 130° C. and atime of about 10 to 100 minutes. With canned foods, the preferredconditions may be a temperature of about 110 to 120° C. and a time ofabout 30 to 300 minutes. With beverages, the preferred conditions may bea temperature of 60° C. and a time of 10 to 30 minutes or a temperatureof 90° C. and a time of about 2 minutes for a beverage having a pH valueof 4 or less; the preferred conditions may be a temperature of 85° C.and a time of 30 to 60 minutes for a beverage having a pH value of 4 to4.6; the preferred conditions may be a temperature of 125° C. and a timeof 5 to 30 minutes or a temperature of 130 to 150° C. and a time ofabout 1 to 2 seconds for a beverage having a pH value of 4.6 or more. Inthe cases of boiled rice, rice cakes, boiled noodles, breads,Japanese-style confections and cakes, flour pastes, aquatic andlivestock paste products, fried eggs, custard puddings, noodle soups,bastes, sauces, subsidiary foods such as water-boiled vegetables, boiledbeans, boiled fishes, fried foods and the like, and foods boiled down insoy, a sterilizing step at a temperature of about 60 to 90° C. for atime of about 10 to 60 minutes may be carried out in some cases, ifrequired, in addition to the heating in the production of any of thesefoods.

The second process of the present invention will be described below.

As described in the first process, 1,5-D-anhydrofructose is anantibacterial substance having a high safety, but the present inventorshave found to obtain the following advantages when 1,5-D-anhydrofructoseis previously subjected to a heat treatment. That is, an antibacterialpower of 1,5-D-anhydrofructose can be further increased, and theantibacterial power is developed at a low concentration of1,5-D-anhydrofructose, as compared with a case where1,5-D-anhydrofructose is not subjected to the heat treatment.Consequently, a food containing 1,5-D-anhydrofructose is difficult toputrefy and at the same time, the antibacterial spectrum becomes wider.Hence, a proliferation-inhibiting effect is exhibited strongly evenagainst gram-negative bacteria, as observed in a reduction in minimumgrowth-inhibiting concentration (MIC) shown in Table A.

TABLE A Influence exerted to minimum growth-inhibiting concentration(MIC) of AF by heat treatment non-heated AF heated AF Bacillus subtillisIAM 1249   3%   1% Staphylococcus aureus FDA 209P 1.5% 0.5% Escherichiacoli NRIC 1023   5%   2% Salmonella typhimurium IFO 12529   4%   2%Streptococcus lactis IAM 1249   3%   1% (In Table A, AF indicates1,5-D-anhydrofructose, and heated AF means AF heated at 120° C. for 10minutes according to a Reference Example 1.)

Heating conditions are preferably a temperature of 50 to 150° C. and atime of 1 second to 100 hours. For example, heat treatment conditionscan be selected from temperature of 50° C. under a normal pressure and atime of 10 minutes to 100 hours, a temperature of 95° C. and a time of 1minute to 10 hours, a temperature of 120° C. under a high pressure and atime of 10 seconds to 2 hours, or a temperature of 130 to 150° C. and atime of 1 second to 30 minutes.

Foods to be used in the second process of the present invention are notparticularly limited, and may be either those not required to be heatedor those to be heated for cooking or sterilization. Examples of thefoods not required to be heated are salads such as potato salad, cutfresh vegetables and fruits, pickles or pickled vegetables, flavoringssuch as raw soy sauce and miso, salted fish guts, vegetables pickled insake lees or miso, fresh fishes or fish slices, dried fishes and meats,fresh livestock meats, seeds of green vegetables. Examples of foods tobe heated are boiled rice, rice cakes, boiled noodles, steamed noodles,breads, bean jams, aquatic and livestock paste products, noodle soups,sauces, tea beverages such as coffee, red tea and green tea, cannedfoods such as water-boiled vegetables, various retort-pouched roux,bottled near-water, fruit juice, fruit drinks, subsidiary foods such asboiled beans or boiled fishes, fried foods, and foods boiled down insoy.

To carry out the second process of the present invention,1,5-D-anhydrofructose heat-treated is first added to a food. A methodfor adding the heat-treated 1,5-D-anhydrofructose to the food is notparticularly limited, and an optimal adding method may be adopted at anoptimal adding time depending on the type of food. For example,1,5-D-anhydrofructose may be added directly to a food to be cooked, ormay be dissolved or dispersed in cooking water and then mixed into afood. To produce a noodle or a bread, 1,5-D-anhydrofructose may be mixedinto a starting material flour for formation. Further, an aqueoussolution of 1,5-D-anhydrofructose may be sprayed to a food, or a foodmay be immersed into the aqueous solution of 1,5-D-anhydrofructose.

The amount of heat-treated 1,5-D-anhydrofructose added is notparticularly limited, but is preferred to be 0.01 to 10% by weight, morepreferably 0.1 to 5% by weight from the viewpoints of the developing ofan antibacterial power and an influence on the taste of a food.

When the heat-treated 1,5-D-anhydrofructose is added to a startingmaterial for a food or to an uncooked food and food is then cooked orfabricated a food having remarkably excellent preservability can beproduced. The heating of a food for cooking and/or sterilization cancontribute to an enhancement in preservability of the food, and exertsno adverse influence to the food as well.

The heating of a food can be carried out, while adding previously heated1,5-D-anhydrofructose to the food, or after addition thereof. Theappropriate heating conditions vary depending on the type of food, andfor example, may be a temperature of 50 to 250° C. and a time of 1second to 300 minutes. The preferred heating conditions, for example,for retort-pouched foods vary depending on the type of food, and may begenerally a temperature of about 120 to 130° C. and a time of about 10to 100 minutes; and for canned foods a temperature of about 110 to 120°C. and a time of about 30 to 300 minutes. With beverages, the preferredheating conditions may be a temperature of 60° C. and a time of 10 to 30minutes or a temperature of 90° C. and a time of about 2 minutes for abeverage having a pH value of 4 or less; a temperature of 85° C. and atime of 30 to 60 minutes for a beverage having a pH value of 4 to 4.6;and a temperature of 125° C. and a time of 5 to 30 minutes or atemperature of 130 to 150° C. and a time of 1 to 2 seconds for abeverage having a pH value of 4.6 or more. In the cases of boiled rice,rice cakes, boiled noodles, breads, Japanese-style confections andcakes, flour pastes, aquatic and livestock paste products, fried eggs,custard puddings, noodle soups, bastes, sauces, water-boiled vegetables,subsidiary foods such as boiled beans, boiled fishes or fried foods, andfoods boiled down in soy, a sterilizing step at a temperature of about60 to 90° C. for a time of about 10 to 60 minutes may be carried out insome cases, if required, in addition to the heating in the production ofany of these foods.

The food preservative of the present invention and the third and fourthprocesses of the present invention will be described below.

The food preservative of the present invention contains

(A) one or both of 1,5-D-anhydrofructose and previously heated1,5-D-anhydrofructose, and

(B) a substance capable of being as a food additive and having anantibacterial activity.

The same components as those described in the first and second processesof the present invention can be used as the component (A).

Examples of the substance (B) having an antibacterial activity andusable as a food additive are amino acids; glycerin lower fatty acidesters; sugar esters; salts of vitamin B1; polyphosphates; ethanol;basic proteins and peptides; antibacterial extract from licorice;extract from red pepper; extract from hop; extract from yucca; extractfrom moso bamboo (thick-stemmed bamboo); extract from grape fruit seed;extract from wasabi (Japanese horseradish) or mustard; acetic acid,lactic acid, fumaric acid and the salts thereof; sorbic acid, benzoicacid and the salts and esters thereof; propionic acid and the saltthereof; chitosan and bacterium DNA. These substances may be used aloneor in combination of two or more. These substances will be describedbelow.

Examples of the amino acids are glycine, cystin, alanine, arginine andlysine. Of these, glycine and alanine are preferred. Such amino acidsmay be of such a grade that they are allowed to be added to a food.

Examples of glycerin lower fatty acid esters are a monoester and diesterof glycerin and a lower fatty acid such as caproic acid, caprylic acid,lauric acid or the like.

As sugar esters, any of esters of sucrose and fatty acids can be used asfar as they are permitted as a food additive.

Examples of salts of vitamin B1 are, for example, sulfates such aslauryl sulfate and cetyl sulfate of vitamin B1.

Examples of polyphosphates are sodium pyrophosphate, sodiummetaphosphate, and sodium polyphosphate.

Examples of basic proteins and peptides are bacteriocins such asprotamine, lysozyme, polylysine and nisin.

The antibacterial extract from licorice, which may be used, is anantibacterial substance produced by using a production process describedin JP-A 60-172928, i.e., an antibacterial substance extracted fromlicorice by an aromatic hydrocarbon, acetone, ethanol and the like. Theantibacterial substance of the extract from licorice is substantiallyunknown at present, but is a substance quite different from glycyrrhizinused as a so-called sweetener.

The extract from red pepper, which may be used, is a substance producedby using a production process described JP-A 4-341169, i.e., awater-soluble fraction extracted from red pepper fruit with an aqueoussolvent.

The extract from hop, which may be used, is a substance extracted fromball flower of hop by cold water, hot water or an organic solvent suchas an alcohol, an ether, acetone or hexane, or a substance extractedfrom ball flower of hop by an alkali aqueous solution of sodiumhydroxide, potassium hydroxide, sodium carbonate, ammonium carbonate,sodium phosphate and the like.

The extract from yucca, the extract from moso bamboo and the extractfrom grape fruit seed, which may be used, are commercially available.

As the extract from wasabi (Japanese horseradish) or mustard, an extractcontaining allyl iso-thiocyanate as a main component may be used.

Examples of salts of acetic acid, lactic acid, fumaric acid, sorbic acidand benzoic acid are sodium salts or potassium salts thereof.

Sorbic acid and benzoic acid and the esters thereof, which may be used,are those commonly used as food additives.

Propionic acid and the salt thereof, which may be utilized, are thosecommonly used as food additives, and those produced, for example, in acheese by fermentation may be also utilized.

Examples of chitosan, which may be used, are those which arecommercially available for usual foods and which may be in a free stateand in the form of any of acetate and glutamate.

DNA extracted from Corynebacterium used by the fermentation of glutamicacid may be used as bacterium DNA, but the bacterium DNA is not limitedthereto, and any of DNAs derived from bacteria may be used.

It is presumed that these substances make up for an antibacterial effectagainst gram-negative bacteria for which 1,5-D-anhydrofructose is not soeffective, or cause the impediment of the synthesis of cell walls ofbacterium or cause leakage of contents of the cells by bonding to cellmembranes of cells of bacterium, or promote the permeation of1,5-D-anhydrofructose into the cells by giving damages cell membranes bydissolution and the like of cell walls, thereby enhancing theantibacterial action. Such an antibacterial effect is further enhancedby heating the food after addition of these substances to the food.

The substance used in combination with 1,5-D-anhydrofructose is notlimited to one type, and the combination of substances of several typesis more effective. The several types of the substances may be selectedproperly in combination depending on the type and composition of a foodused, an anticipated pollution—or deterioration—causing microorganism, apH value, a water activity, and a required preservation temperature andpreservation period.

The preferred proportion of the components in the present invention isas follows: For example, the amino acid is used in an amount of 0.01 to100 parts by weight; the glycerin lower aliphatic ester, the sugar esterand the salt of vitamin B1 are used in an amount of 0.001 to 10 parts byweight, respectively; the polyphosphate is used in an amount of 0.01 to100 parts by weight; ethanol is used in an amount of 0.01 to 100 partsby weight; the basic protein and peptide are used in an amount of 0.001to 10 parts by weight; the antibacterial extract from licorice is usedin an amount of 0.005 to 50 parts by weight; the extract from red pepperis used in an amount of 0.005 to 50 parts by weight the hop extract isused in an amount of 0.005 to 50 parts by weight; the yucca extract isused in an amount of 0.005 to 50 parts by weight; the moso bambooextract is used in an amount of 0.005 to 50 parts by weight; the grapefruit seed extract is used in an amount of 0.005 to 50 parts by weight;the wasabi (Japanese horseradish) or mustard extract is used in anamount of 0.000001 to 0.005 parts by weight in terms ofally-isothiocyanate; acetic acid, lactic acid, fumaric acid or the saltsthereof is used in an amount of 0.01 to 50 parts by weight; sorbic acid,benzoic acid, propionic acid and the salt or ester thereof are used inan amount of 0.001 to 50 parts by weight; chitosan is used in an amountof 0.01 to 100 parts by weight; and bacterium DNA is used in an amountof 0.01 to 10 parts by weight, all per part by weight of1,5-D-anhydrofructose.

The food preservative of the present invention has an antibacterialspectrum widened and an antibacterial effect enhanced synergistically,and is excellent and high in safety. In addition, the heating conditionsfor a food, particularly the heating conditions for sterilization can bemoderated by adding the food preservative of the present invention, andas a result, the deterioration of the quality of the food can beprevented. Further, the antibacterial effect can be further enhanced byheating the food for cooking or sterilization after addition of the foodpreservative to the food.

The process for producing a food having excellent preservabilityaccording to the present invention (the third process) is carried out byadding the food preservative of the present invention to, and mixingwith, the food. Even if 1,5-D-anhydrofructose and a substance having anantibacterial activity as described above are added separately to afood, a similar effect can be achieved.

In the food preservative of the present invention, 1,5-D-anhydrofructoseis added to a food in an amount preferably in a range of 0.01 to 10% byweight, more preferably in a range of 0.1 to 5% by weight based on theentire amount of a food. If the amount of 1,5-D-anhydrofructose added islower than 0.01% by weight, the antibacterial effect may beinsufficient. If the amount exceeds 10% by weight, the food is feltbitter.

In the third process of the present invention, the food can be heatedwhile adding the food preservative or after addition thereof. Theantibacterial effect of the food preservative of the present inventionis enhanced by heating and the preservability of the food containingthus heat-treated food preservative is enhanced greatly. This ispresumed as being attributable to the effect of the heat sterilizationand the effect of suppressing or inhibiting the proliferation of theputrefying bacteria during subsequent preservation of the food worksynergistically in the presence of the antibacterial substance.

In the third process of the present invention, “heating” means theheating of a food for cooking the food into an edible food by steaming,boiling, roasting, broiling or oil-conditioning, as well as the heatingof a food for sterilization at a high temperature and under a highpressure, for example, for canning, bottling and retort-pouching, andfurther includes the reheating of a food for sterilization after beingpackaged. The appropriate heating conditions vary depending on the typeof food, but may be a temperature of 50 to 250° C. and a time of 1second to 300 minutes. With retort-pouched foods, the preferredconditions vary depending on the type of food, but may be generally atemperature of about 120 to 130° C. and a time of about 10 to 100minutes. With canned foods, the preferred conditions may be atemperature of about 110 to 120° C. and a time of about 30 to 300minutes. With beverages, the preferred conditions may be a temperatureof 60° C. and a time of 10 to 30 minutes, or a temperature of 90° C. anda time of about 2 minutes for a beverage having a pH value of 4 or less;the preferred conditions may be a temperature of 85° C. and a time of 30to 60 minutes for a beverage having a pH value of 4 to 4.6; thepreferred conditions may be a temperature of 125° C. and a time of 5 to30 minutes or a temperature of 130 to 150° C. and a time of about 1 to 2seconds for a beverage having a pH value of 4.6 or more. In the cases ofboiled rice, rice cakes, boiled noodles, breads, Japanese-styleconfections and cakes, flour pastes, aquatic and livestock pasteproducts, fried eggs, custard puddings, noodle soups, bastes, sauces,water-boiled vegetables, subsidiary foods such as boiled beans, boiledfishes, fried foods and the like, and foods boiled down in soy, asterilizing step at a temperature of 60 to 90° C. for a time of about 10to 60 minutes may be carried out in some cases, if required, in additionto the heating in the production of any of these foods.

The fourth process of the present invention can be carried out bypreserving the food produced in the third process of the presentinvention. The food produced in the third process of the presentinvention has an excellent preservability and hence, the fourth processprovides a process excellent as a food preserving process.

EXAMPLES

The present invention will be described in further detail by way ofExamples, but is not limited to Examples which will be described below.In the Examples, “part” and “%” are by weight. The number of livingbacteria was measured at 300° C. for 48 hours in a standard agar culturemedium, and the number of molds and yeast fungi was measured at 30° C.for 72 hours in a potato dextrose agar culture medium.

Reference Example 1 (Preparation of 1,5-D-anhydrofructose)

Lyase used was a specimen produced extracted from a red alga (Gracilariaverrucosa) and purified a single band by SDS-PAGE. A debranching enzymewas added to an aqueous solution of maltodextrin having a DE value ofabout 20 (containing 30% of solids), and they were reacted at 60° C. for4 hours. Then, the reaction solution was cooled to 40° C. andthereafter, lyase was added thereto so as to secure 15 U/gram of starch,and the incubation was conducted for 25 hours. After completion of theenzyme reaction, the reaction solution was treated with activated carbonto adsorb a colored matter, and an insoluble matter was removed byfilteration to produce a sample. The obtained sample contained 30% ofsolids, and the sugar composition thereof was quantitatively measured byHPLC. The result showed that 72% was 1,5-D-anhydrofructose; 18% wasglucose; and 10% was high molecular maltodextrin. The sample was used as1,5-D-anhydrofructose (which will be abbreviated as AF hereinafter, andthe amount of AF added is shown in terms of solids, unless otherwiseindicated) in Examples and Test Examples which will be describedhereinafter.

In the Examples, the hop extract, chitosan, bacterium DNA, licoriceextract, protamine and red pepper extract were manufactured by AsamaKasei, Co.; the polylysine was produced by Chisso, Corp.; the lysozymewas produced by Wako Pure Chemical Ind., Ltd.; the moso bamboo extractwas produced by NOF Corp.; the grape fruit seed extract was produced byBiochem.Co., Ltd., the yucca extract was produced by Maruzen Kasei, Co.;and the nisin was a 10% dilute solution produced by Aplin&Barrett.Inc.The other substances used were standardized products specified as foodadditives.

Example 1

A salt-preserved Japanese radish (pickled radish called “takuan”) wasdesalted under running water, until the salt content reached 3%. Theresulting radish was immersed in a flavoring solution prescribed asshown in Table 1 in a refrigerator for 3 days. Then, a preservativeshown in Table 2 was added at a concentration four times that shown inTable 2 to the flavoring solution shown in Table 1, and 300 grams of thepickled radish was added to 100 ml of the resulting solution and sacked(the concentration of the preservative was a value shown in Table 2).Various test product groups were prepared in a similar process andpreserved at 20° C., and the number of days of preservation was examinedby observing the turbidity of the pickled radish liquid, the swelling ofthe sack and the like. Results are shown in Table 2.

TABLE 1 Component Concentration (% by weight) Soy sauce 1.0 Salt 3.0Vinegar 0.5 Glycyrrhizine 0.02 Sweet sake 0.5 Yeast extract 0.5 HAP 1.0Water 93.48 (pH 4.8)

TABLE 2 Test AF Et. H.E L.S of V Ch. B.DNA LEX S.C Num. of No. (%) (%)(%) (%) (%) (%) (%) (%) Pre.Ds 1 Pro. of Co. 3 — — — — — — — 3 2 Pro. ofCo. — 3.0 — — — — — — 3 3 Pro. of Co. — — 0.05 — — — — — 3 4 Pro. of Co.— — — 0.01 — — — — 4 5 Pro. of Co. — — — — 0.2 — — — 3 6 Pro. of Co. — —— — — 0.1 — — 4 7 Pro. of Co. — — — — — — 0.2 — 3 8 Pro. of Co. — — — —— — — 0.05 4 9 Pro. of In. 3 3.0 — — — — — — 10 10 Pro. of In. 3 — 0.05— — — — — 10 11 Pro. of In. 3 — — 0.01 — — — — 12 12 Pro. of In. 3 — — —0.2 — — — 10 13 Pro. of In. 3 — — — — 0.1 — — 10 14 Pro. of In. 3 — — —— — 0.2 — 11 15 Pro. of In. 3 — — — — — — 0.05 11 16 Pro. of In. 3 3.00.05 — — — — — 20 17 Pro. of In. 3 3.0 — 0.01 — — — — 22 18 Pro. of In.3 3.0 — — 0.2 — — — 20 19 Pro. of In. 3 3.0 — — — 0.1 — — 23 20 Pro. ofIn. 3 3.0 — — — — 0.2 — 19 21 Pro. of In. 3 3.0 — — — — — 0.05 21 22Pro. of In. 3 — 0.05 0.01 — — — — 22 23 Pro. of In. 3 — 0.05 — 0.2 — — —20 24 Pro. of In. 3 — 0.05 — — 0.1 — — 23 25 Pro. of In. 3 — 0.05 — — —0.2 — 20 26 Pro. of In. 3 — 0.05 — — — — 0.05 22 27 Pro. of In. 3 — —0.01 0.2 — — — 23 28 Pro. of In. 3 — — 0.01 — 0.1 — — 27 29 Pro. of In.3 — — 0.01 — — 0.2 — 24 30 Pro. of In. 3 — — 0.01 — — — 0.05 25 31 Pro.of In. 3 — — — 0.2 0.1 — — 22 32 Pro. of In. 3 — — — 0.2 — 0.2 — 22 33Pro. of In. 3 — — — 0.2 — — 0.05 22 34 Pro. of In. 3 — — — — 0.1 0.2 —22 35 Pro. of In. 3 — — — — 0.1 — 0.05 23 36 Pro. of In. 3 — — — — — 0.20.05 21 Et. = ethanol; H.E = hop extract; L.S of V = lauryl sulfate ofvitamin B1; Ch. = chitosan; B. DNA = bacterium DNA; LEX = licoriceextract; S.C = sorboic acid; Num. of Pre.Ds = number of preservationdays; Pro. of Co. = Product of control; and Pro. of In. = Product of thepresent invention

Example 2

Various preservative components shown in Table 3 were added in theproportions shown in Table 3 to a basic composition of a hamburgerprepared by blending 1,000 g of beef and pork ground together, 300 g ofonion, 60 g of wheat flour and 50 g of water, and the pH of theresulting material was adjusted to 5.8 by hydrochloric acid or causticsoda. Then, hamburgers each weighing 30 grams were formed from the abovematerial and steamed for 25 minutes and cooled. The five pieces of thusproduced hamburgers per test division were prepared, and preserved at25° C. and subjected to a preservation test by checking theirappearances and smells. Each of test results is shown in Table 3 by anaverage value of preservation days for the five hamburgers.

When the preservative of the present invention was added, no adverseinfluence to the quality due to the addition was observed.

TABLE 3 Test No. AF(%) S.A.(%) S.L.(%) S.F.(%) P.EX.(%) Pr.(%) S.ML.(%)Num. of Pre.Ds 1 Pro. of Co. 2 — — — — — — 3.8 2 Pro. of Co. — 0.5 — — —— — 3.8 3 Pro. of Co. — — 0.5 — — — — 3.6 4 Pro. of Co. — — — 0.5 — — —4.4 5 Pro. of Co. — — — — 0.5 — — 3.2 6 Pro. of Co. — — — — — 0.03 — 3.67 Pro. of Co. — — — — — — 0.1 3.2 8 Pro. of In. 2 0.5 — — — — — 10.5 9Pro. of In. 2 — 0.5 — — — — 10.0 10 Pro. of In. 2 — — 0.5 — — — 13.2 11Pro. of In. 2 — — — 0.5 — — 10.9 12 Pro. of In. 2 — — — — 0.03 — 12.5 13Pro. of In. 2 — — — — — 0.1 10.3 14 Pro. of In. 2 0.5 0.5 — — — — 23.315 Pro. of In. 2 0.5 — 0.5 — — — 24.6 16 Pro. of In. 2 0.5 — — 0.5 — —21.1 17 Pro. of In. 2 0.5 — — — 0.03 — 23.7 18 Pro. of In. 2 0.5 — — — —0.1 22.4 19 Pro. of In. 2 — 0.5 0.5 — — — 25.3 20 Pro. of In. 2 — 0.5 —0.5 — — 21.1 21 Pro. of In. 2 — 0.5 — — 0.03 — 23.8 22 Pro. of In. 2 —0.5 — — — 0.1 20.0 23 Pro. of In. 2 — — 0.5 0.5 — — 23.7 24 Pro. of In.2 — — 0.5 — 0.03 — 31.4 25 Pro. of In. 2 — — 0.5 — — 0.1 20.2 26 Pro. ofIn. 2 — — — 0.5 0.03 — 22.9 27 Pro. of In. 2 — — — 0.5 — 0.1 21.1 28Pro. of In. 2 — — — — 0.03 0.1 23.3 S.A. = sodium acetate; S.L. = sodiumlactate; S.F. = sodium fumarate; P.EX. = red pepper extract; Pr. =protamine; S.ML. = sucrose monolaurate Num. of Pre.Ds = number ofpreservation days Pro. of Co. = Product of control; Pro. of In. =Product of the present invention

Example 3

Various preservative components shown in Table 4 were added in theproportions shown in Table 4 to a basic composition of a custard creamproduced by blending 160 g of a yoke, 1,440 g of milk, 65 g of wheatflour, 65 g of starch and 600 g of sucrose, and the mixtures were boiledat a temperature of 85 to 95° C. for about 10 minutes and cooled. Theresulting custard creams were divided into five plastic vessels per testdivision, and the vessels were lidded softly and the custard creams werepreserved at 15° C. for a preservation test in which their appearancesand smells were checked. The test results are shown in Table 4 by anaverage number of preservation days for the five custard creams.

TABLE 4 Test No. AF(%) Gl.(%) P.L.(%) G.C.(%) S.P.(%) Ly.(%) Num. ofPre.Ds 1 Pro. of Co. 0.75 — — — — — 3.0 2 Pro. of Co. — 0.5 — — — — 2.73 Pro. of Co. — — 0.02 — — — 3.0 4 Pro. of Co. — — — 0.04 — — 3.3 5 Pro.of Co. — — — — 0.1 — 2.1 6 Pro. of Co. — — — — — 0.03 2.8 7 Pro. of In.0.75 0.5 — — — — 8.0 8 Pro. of In. 0.75 — 0.02 — — — 8.9 9 Pro. of In.0.75 — — 0.04 — — 9.0 10 Pro. of In. 0.75 — — — 0.1 — 9.1 11 Pro. of In.0.75 — — — — 0.03 9.6 12 Pro. of In. 0.75 0.5 0.02 — — — 20.1 13 Pro. ofIn. 0.75 0.5 — 0.04 — — 22.3 14 Pro. of In. 0.75 0.5 — — 0.1 — 20.6 15Pro. of In. 0.75 0.5 — — — 0.03 23.7 16 Pro. of In. 0.75 — 0.02 0.04 — —22.6 17 Pro. of In. 0.75 — 0.02 — 0.1 — 21.5 18 Pro. of In. 0.75 — 0.02— — 0.03 27.4 19 Pro. of In. 0.75 — — 0.04 0.1 — 20.2 20 Pro. of In.0.75 — — 0.04 — 0.03 22.7 21 Pro. of In. 0.75 — — — 0.1 0.03 22.9 Gl. =glysine; P.L. = polylysine; G.C. = caprylic monoglyceride; S.P. = sodiumpolyphosphate; Ly. = lysozyme; Num. of Pre.Ds = number of preservationdays; Pro. of Co. = Product of control; Pro. of In. = Product of thepresent invention

Example 4

Various preservative components shown in Table 5 were added in theproportions shown in Table 5 to a basic composition produced by blending500 g of an extra-strength flour, 160 ml of water and 5 g of a brinepowder. The mixture was mixed sufficiently and placed into a small-sizednoodle-making machine to form noodle strands. The noodle strands wereboiled in boiling water for 4 minutes and then cooled. The boilednoodles were drained and then put into polyethylene sacks, which werethen sealed. Ten sacks per test division were preserved in aconstant-temperature vessel at 25° C., and change in their appearancewas observed. The test samples in the ten sacks were evaluated byexamining the number of days taken till the occurrence of thediscoloration and the softening or the generation of slime and mold atone point on the test samples and taking an average value of the numbersof days as an effective number of preservation days. Results are shownin Table 5.

TABLE 5 Test AF Ly. Pr. Gl. Al. Num. of No. (%) (%) (%) (%) (%) Pre.DsNon-added — — — — — 2.2 1 Pro. of Co. 3 — — — — 3.5 2 Pro. of Co. — 0.05— — — 2.5 3 Pro. of Co. — — 0.05 — — 3.4 4 Pro. of Co. — — — 0.5 — 2.6 5Pro. of Co. — — — — 1 3.5 6 Pro. of In. 3 0.05 — — — 8.0 7 Pro. of In. 3— 0.05 — — 9.5 8 Pro. of In. 3 — — 0.5 — 8.1 9 Pro. of In. 3 — — — 1 7.910 Pro. of In. 3 0.05 — 0.5 — 11.4 11 Pro. of In. 3 — 0.05 0.5 — 14.1Ly. = lysozyme; Pr. = protamine; Gl. = glysine; Al. = Alanine; Num. ofPre.Ds = number of preservation days; Pro. of Co. = Product of control;Pro. of In. = Product of the present invention

Example 5

A commercially available and unsealed quadruply concentrated noodle soupwas diluted four times with sterile water. In this case, AF waspreviously added so as to be 1.5%. Thirty 200 ml volume Erlenmeyerflasks with a stopper each containing such noodle soup in an amount of100 ml were prepared. As shown in Table 6, chemicals were added to eachof test sample Nos. 1 to 36. Then, the test sample Nos. 1 to 18 were notheated (remained unheated and unsterilized), and the test sample Nos. 19to 36 were heated for 10 minutes, i.e., sterilized by hot water. Whenthe test sample Nos. 19 to 36 were cooled, a lactobacillus-mixedsolution separated from the deteriorated noodle soup was inoculated inan amount of 0.01 ml into each of the test sample Nos. 1 to 36. Theflasks of the test sample Nos. 1 to 36 were placed into an incubatorhaving a temperature of 30° C. for a preservation test. The preservationtest was conducted by checking the turbidity of the noodle soup solutionas the guideline. Results are as shown in Table 6.

TABLE 6 Test No. AF(%) SA(%) BE(%) GFE(%) YE(%) N(%) BA(%) Nnm. ofPre.Ds Unsterilized 1 Pro. of Co. 1.5 — — — — — — 2 2 Pro. of Co. — 0.5— — — — — 2 3 Pro. of Co. — — 0.2 — — — — 3 4 Pro. of Co. — — — 0.1 — —— 2 5 Pro. of Co. — — — — 0.05 — — 2 6 Pro. of Co. — — — — — 0.02 — 4 7Pro. of Co. — — — — — — 0.05 5 8 Pro. of In. 1.5 0.5 — — — — — 6 9 Pro.of In. 1.5 — 0.2 — — — — 8 10 Pro. of In. 1.5 — — 0.1 — — — 6 11 Pro. ofIn. 1.5 — — — 0.05 — — 6 12 Pro. of In. 1.5 — — — — 0.02 — 10 13 Pro. ofIn. 1.5 — — — — — 0.05 12 14 Pro. of In. 1.5 0.5 0.2 — — — — 14 15 Pro.of In. 1.5 0.5 — 0.1 — — — 14 16 Pro. of In. 1.5 0.5 — — 0.05 — — 13 17Pro. of In. 1.5 0.5 — — — 0.02 — 18 18 Pro. of In. 1.5 0.5 — — — — 0.0520 19 Pro. of Co. 1.5 — — — — — — 4 20 Pro. of Co. — 0.5 — — — — — 2 21Pro. of Co. — — 0.2 — — — — 3 22 Pro. of Co. — — — 0.1 — — — 2 23 Pro.of Co. — — — — 0.05 — — 2 24 Pro. of Co. — — — — — 0.02 — 4 25 Pro. ofCo. — — — — — — 0.05 6 26 Pro. of In. 1.5 0.5 — — — — — 10 27 Pro. ofIn. 1.5 — 0.2 — — — — 12 28 Pro. of In. 1.5 — — 0.1 — — — 10 29 Pro. ofIn. 1.5 — — — 0.05 — — 10 30 Pro. of In. 1.5 — — — — 0.02 — 14 31 Pro.of In. 1.5 — — — — — 0.05 16 32 Pro. of In. 1.5 0.5 0.2 — — — — 17 33Pro. of In. 1.5 0.5 — 0.1 — — — 22 34 Pro. of In. 1.5 0.5 — — 0.05 — —18 35 Pro. of In. 1.5 0.5 — — — 0.02 — 28 36 Pro. of In. 1.5 0.5 — — — —0.05 24 SA = sodium acetate; BE = moso bamboo extract; GFE = grape fruitseed extract; YE = yucca extract; N = nisin; BA = benzoic acid; and Nnm.of Pre.Ds = number of preservation days; Pro. of Co. = Product ofcontrol; Pro. of In. = Product of the present invention

Reference Example 2 (Preparation of 1,5-D-anhydrofructose Heat-Treated)

Lyase used was a specimen prepared by extracting from a red alga(Gracilaria verrcosa) and purified to form a single band by SDS-PAGE. Adisbranching enzyme was added to an aqueous solution of maltodextrinhaving a DE value of about 20 (containing 30% of solids), and they werereacted each other at 60° C. for 4 hours. Then, the reaction solutionwas cooled to 40° C. and then, lyase was added in an amount of 15 U/gramof starch, and the incubation was conducted for 25 hours. Aftercompletion of the enzyme reaction, the reaction solution was treatedwith activated carbon to adsorb a colored material, and an insolublematter was then filtered off to obtain a sample. The obtained samplecontained 30% of solids, and a quantitative analysis for its sugarcomposition using HPLC showed that 72% was 1,5-D-anhydrofructose, 18%was glucose, and 10% was high-molecular maltodextrin. This sample washeat treated at 55° C. for 10 minutes by hot water. The resulting samplewas called AF-055, and the sample resulting from the heating at 90° C.for 10 minutes was called AF-090. The sample resulting from the heatingat 120° C. for 10 minutes in an autoclave was called AF-120. Each ofthese samples was used as 1,5-D-anhydrofructose heat-treated in Exampleswhich will be described hereinafter. 1,5-D-anhydrofructose not heated iscalled AF-000. The amount of each 1,5-D-anhydrofructose added wasindicated in terms of solids.

Example 6

A salt-preserved Japanese radish (pickled radish called “takuan”) wasdesalted under running water until the salt content reached 3%. Theresulting radish was immersed in a flavoring solution prescribed asshown in Table 1 in a refrigerator for 3 days. Then, a preservativeshown in Table 7 was added at a concentration four times that shown inTable 7 to the flavoring solution shown in Table 1, and 300 grams of thepickled radish immersed in the flavoring solution was added to 100 ml ofthe resulting solution and sacked (the concentration of the preservativewas a value shown in Table 7). In this Example, the1,5-D-anhydrofructose heated at 55° C. for 10 minutes (i.e., AF-055) wasused. Various test product groups were prepared in a similar process andpreserved at 20° C., and the number of days of preservation was examinedby observing the turbidity of the pickled radish liquid, the swelling ofthe sack and the like. Results are shown in Table 7.

TABLE 7 Test Num. of No. AF-055(%) Et.(%) H.E(%) L.S of V(%) Ch.(%)B.DNA(%) LEX(%) S.C(%) Pre.Ds 1 Pro. of Co. 1.5 — — — — — — — 3 2 Pro.of Co. — 3.0 — — — — — — 3 3 Pro. of Co. — — 0.05 — — — — — 3 4 Pro. ofCo. — — — 0.01 — — — — 4 5 Pro. of Co. — — — — 0.2 — — — 3 6 Pro. of Co.— — — — — 0.1 — — 4 7 Pro. of Co. — — — — — — 0.2 — 3 8 Pro. of Co. — —— — — — — 0.05 4 9 Pro. of In. 1.5 3.0 — — — — — — 9 10 Pro. of ln. 1.5— 0.05 — — — — — 9 11 Pro. of In. 1.5 — — 0.01 — — — — 12 12 Pro. of In.1.5 — — — 0.2 — — — 10 13 Pro. of In. 1.5 — — — — 0.1 — — 11 14 Pro. ofIn. 1.5 — — — — — 0.2 — 11 15 Pro. of In. 1.5 — — — — — — 0.05 12 16Pro. of In. 1.5 3.0 0.05 — — — — — 18 17 Pro. of In. 1.5 3.0 — 0.01 — —— — 21 18 Pro. of In. 1.5 3.0 — — 0.2 — — — 19 19 Pro. of In. 1.5 3.0 —— — 0.1 — — 21 20 Pro. of In. 1.5 3.0 — — — — 0.2 — 19 21 Pro. of In.1.5 3.0 — — — — — 0.05 25 22 Pro. of In. 1.5 — 0.05 0.01 — — — — 20 23Pro. of In. 1.5 — 0.05 — 0.2 — — — 20 24 Pro. of In. 1.5 — 0.05 — — 0.1— — 22 25 Pro. of In. 1.5 — 0.05 — — — 0.2 — 18 26 Pro. of In. 1.5 —0.05 — — — — 0.05 24 27 Pro. of In. 1.5 — — 0.01 0.2 — — — 22 28 Pro. ofIn. 1.5 — — 0.01 — 0.1 — — 25 29 Pro. of In. 1.5 — — 0.01 — — 0.2 — 2230 Pro. of In. 1.5 — — 0.01 — — — 0.05 26 31 Pro. of In. 1.5 — — — 0.20.1 — — 20 32 Pro. of In. 1.5 — — — 0.2 — 0.2 — 21 33 Pro. of In. 1.5 —— — 0.2 — — 0.05 26 34 Pro. of In. 1.5 — — — — 0.1 0.2 — 20 35 Pro. ofIn. 1.5 — — — — 0.1 — 0.05 25 36 Pro. of In. 1.5 — — — — — 0.2 0.05 24Et. = ethanol; H.E = hop extract; L.S of V = lauryl sulfate of vitaminB₁; Ch. = chitosan; B. DNA = bacterium DNA; LEX = licorice extract; S.C= sorboic acid; Num. of Pre.Ds = number of preservation days; and Pro.of In. = Product of the present invention

Example 7

Various preservative components shown in Table 8 were added in theproportions shown in Table 8 to a basic composition of a hamburgerprepared by blending 1,000 g of beef and pork ground together, 300 g ofonion, 60 g of wheat flour and 50 g of water, and the pH of theresulting material was adjusted to 5.8 by hydrochloric acid or causticsoda. Then, hamburgers each weighing 30 grams were formed from the abovematerial and steamed for 25 minutes and cooled. The five pieces of thusproduced hamburgers per test division were prepared, and preserved at25° C. and subjected to a preservation test by checking theirappearances and smells. In this Example, the 1,5-D-anhydrofructoseheated at 90° C. for 10 minutes (i.e., AF-090) was used, and the testresults are shown in Table 8 by an average value of preservation daysfor the five hamburgers.

When the preservative of the present invention was added, no adverseinfluence to the quality due to the addition was observed.

TABLE 8 Test Num. of No. AF-090(%) S.A.(%) S.L.(%) S.F(%) P.EX.(%)Pro.(%) S.ML.(%) Pre.Ds 1 Pro. of Co. 1 — — — — — — 3.7 2 Pro. of Co. —0.5 — — — — — 3.6 3 Pro. of Co. — — 0.5 — — — — 3.6 4 Pro. of Co. — — —0.5 — — — 4.2 5 Pro. of Co. — — — — 0.5 — — 3.4 6 Pro. of Co. — — — — —0.03 — 3.5 7 Pro. of Co. — — — — — — 0.1 3.0 8 Pro. of In. 1 0.5 — — — —— 11.6 9 Pro. of In. 1 — 0.5 — — — — 12.0 10 Pro. of In. 1 — — 0.5 — — —13.5 11 Pro. of In. 1 — — — 0.5 — — 12.1 12 Pro. of In. 1 — — — — 0.03 —14.4 13 Pro. of In. 1 — — — — — 0.1 11.7 14 Pro. of In. 1 0.5 0.5 — — —— 24.1 15 Pro. of In. 1 0.5 — 0.5 — — — 25.5 16 Pro. of In. 1 0.5 — —0.5 — — 22.0 17 Pro. of In. 1 0.5 — — — 0.03 — 24.9 18 Pro. of In. 1 0.5— — — — 0.1 23.4 19 Pro. of In. 1 — 0.5 0.5 — — — 25.5 20 Pro. of In. 1— 0.5 — 0.5 — — 22.7 21 Pro. of In. 1 — 0.5 — — 0.03 — 25.1 22 Pro. ofIn. 1 — 0.5 — — — 0.1 21.3 23 Pro. of In. 1 — — 0.5 0.5 — — 24.8 24 Pro.of In. 1 — — 0.5 — 0.03 — 33.5 25 Pro. of In. 1 — — 0.5 — — 0.1 22.1 26Pro. of In. 1 — — — 0.5 0.03 — 24.7 27 Pro. of In. 1 — — — 0.5 — 0.121.8 28 Pro. of In. 1 — — — — 0.03 0.1 25.4 S.A = sodium acetate; S.L. =sodium lactate; S.F. = sodium fumarate; P.EX. = red pepper extract; Pro.= protamine; S.ML. = sucrose monolaurate; Num of Pre. Ds = number ofpreservation days; Pro. of Co. = Product of control; Pro. of In. =Product of the present invention

Example 8

Various preservative components shown in Table 9 were added in theproportions shown in Table 9 to a basic composition of a custard creamprepared by blending 160 g of a yoke, 1,440 g of milk, 65 g of wheatflour, 65 g of starch and 600 g of sucrose, and the mixtures were boiledat a temperature of 85 to 95° C. for about 10 minutes and cooled. Theresulting materials were divided into five plastic vessels per testdivision, and the vessels were lidded softly and the content waspreserved at 150° C. for a preservation test in which their appearancesand smells were checked. In this Example, the 1,5-D-anhydrofructoseheated at 90° C. for 10 minutes (i.e., AF-090) was used, and the testresults are shown in Table 9 by an average number of preservation daysfor the five custard creams.

TABLE 9 Test No. AF-090(%) Gl.(%) P.L.(%) G.C.(%) S.P.(%) Ly.(%) Num. ofPre.Ds 1 Pro. of Co. 1.5 — — — — — 3.2 2 Pro. of Co. — 0.5 — — — — 2.8 3Pro. of Co. — — 0.02 — — — 3.2 4 Pro. of Co. — — — 0.04 — — 3.6 5 Pro.of Co. — — — — 0.1 — 2.0 6 Pro. of Co. — — — — — 0.03 3.0 7 Pro. of In.1.5 0.5 — — — — 8.6 8 Pro. of In. 1.5 — 0.02 — — — 9.3 9 Pro. of In. 1.5— — 0.04 — — 9.9 10 Pro. of In. 1.5 — — — 0.1 — 9.3 11 Pro. of In. 1.5 —— — — 0.03 10.2 12 Pro. of In. 1.5 0.5 0.02 — — — 22.8 13 Pro. of In.1.5 0.5 — 0.04 — — 24.7 14 Pro. of In. 1.5 0.5 — — 0.1 — 22.2 15 Pro. ofIn. 1.5 0.5 — — — 0.03 25.3 16 Pro. of In. 1.5 — 0.02 0.04 — — 24.2 17Pro. of In. 1.5 — 0.02 — 0.1 — 21.1 18 Pro. of In. 1.5 — 0.02 — — 0.0329.7 19 Pro. of In. 1.5 — — 0.04 0.1 — 20.9 20 Pro. of In. 1.5 — — 0.04— 0.03 23.3 21 Pro. of In. 1.5 — — — 0.1 0.03 23.3 Gl. = glysine; P.L. =polylysine; G.C. = capric monoglyceride; S.P. = sodium polyphosphate;Ly. = lysozyme; Num. of Pre.Ds = number of preservation days; Pro. ofCo. = Product of control; Pro. of In. = Product of the present invention

Example 9

Various preservative components shown in Table 5 were added in theproportions shown in Table 10 to a basic composition of Chinese noodlesproduced by blending 500 g of extra-strength flour, 160 ml of water and5 g of a brine powder. The mixture was mixed sufficiently and placedinto a small-sized noodle-making machine to form noodle strands. Thenoodles were boiled in boiling water for 4 minutes and then cooled. Theobtained noodles were drained and then put into polyethylene sacks,which were then sealed. Ten sacks per test division were preserved in aconstant-temperature vessel at 25° C., and change in their appearanceswas observed. In this Example, the 1,5-D-anhydrofructose heated at 90°C. for 10 minutes (i.e., AF-090) was used. The evaluation was carriedout in the same manner as Example 4. The test samples in the ten sackswere evaluated by examining the number of days taken till the occurrenceof the discoloration and the softening or the generation of slime andmold at one point on the test samples and taking an average value of thenumbers of days as an effective number of preservation days. Results areshown in Table 10.

TABLE 10 Test No. AF-090(%) Ly. (%) Pr. (%) Gl. (%) Al. (%) Num. ofPre.Ds Non-added — — — — — 2.3 1 Pro. of Co. 1.5 — — — — 3.7 2 Pro. ofCo. — 0.05 — — — 2.6 3 Pro. of Co. — — 0.05 — — 3.7 4 Pro. of Co. — — —0.5 — 2.7 5 Pro. of Co. — — — — 1 3.5 6 Pro. of In. 1.5 0.05 — — — 9.1 7Pro. of In. 1.5 — 0.05 — — 10.2 8 Pro. of In. 1.5 — — 0.5 — 9.9 9 Pro.of In. 1.5 — — — 1 9.1 10 Pro. of In. 1.5 0.05 — 0.5 — 12.7 11 Pro. ofIn. 1.5 — 0.05 0.5 — 14.5 Ly. = lysozyme; Pr. = protamine; Gl. =glysine; Al. = Alanine; Num. of Pre.Ds = number of preservation days;Pro. of Co. = Product of control; Pro. of In. = Product of the presentinvention

Example 10

80 Grams of a powdery soup stock (produced by Yamaki, Co.) and 400 ml ofRaw soy sauce (manufactured by Fukuoka Prefecture Brewage Association)were added to 2 liters of water to prepare a noodle soup. Each of aproduct of a control and a product of the present invention was dividedin an amount of 100 ml into beakers. Chemicals were added to the beakersaccording to a prescription shown in Table 11 to produce test samplegroups (Nos. 1 to 18). In this case, the 1,5-D-anhydrofructose heated at120° C. for 10 minutes (i.e., AF-120) was used.

Eight heat-resistant polyethylene sacks per each of test Nos. 1 to 18were prepared, and the noodle soup was charged in an amount of 10 mlinto each of the eight sacks, which were then heat-sealed. The contentsof the sacks were preserved at 30° C. without being subjected to ahot-water sterilization, for a preservation test in which the liquidturbidity and the swelling were observed. Results are shown in Table 11.The observation was continued until all of the contents of the eightsacks were changed in quality, and an average number of preservationdays is shown as a number of preservation days.

TABLE 11 Test No. AF-120(%) SA(%) BE(%) GFE(%) YE(%) N(%) BA(%) Nnm. ofPre.Ds 1 Pro. of Co. 0.75 — — — — — — 3.6 2 Pro. of Co. — 0.5 — — — — —2.2 3 Pro. of Co. — — 0.2 — — — — 2.6 4 Pro. of Co. — — — 0.1 — — — 1.95 Pro. of Co. — — — — 0.05 — — 2.4 6 Pro. of Co. — — — — — 0.02 — 4.9 7Pro. of Co. — — — — — — 0.05 5.1 8 Pro. of In. 0.75 0.5 — — — — — 8.5 9Pro. of In. 0.75 — 0.2 — — — — 8.5 10 Pro. of In. 0.75 — — 0.1 — — — 7.111 Pro. of In. 0.75 — — — 0.05 — — 8.0 12 Pro. of In. 0.75 — — — — 0.02— 11.3 13 Pro. of In. 0.75 — — — — — 0.05 13.2 14 Pro. of In. 0.75 0.50.2 — — — — 16.6 15 Pro. of In. 0.75 0.5 — 0.1 — — — 14.0 16 Pro. of In.0.75 0.5 — — 0.05 — — 15.3 17 Pro. of In. 0.75 0.5 — — — 0.02 — 22.0 18Pro. of In. 0.75 0.5 — — — — 0.05 25.5 SA = sodium acetate; BE = mosobamboo extract; GFE = Grape fruit seed extract; YE = yucca extract; N =nisin; BA = benzoic acid; and Nnm. of Pre.Ds = number of preservationdays; Pro. of Co. = Product of control; Pro. of In. = Product of thepresent invention

Test Example 1 (Influence of Heating Time and Heating Temperature toAntibacterial Power of AF)

AF was subjected to an antibacterial power test using a turbidimetry.More specifically, a soybean-casein digest broth medium (having a pHvalue of 5.5) previously sterilized and 1% of AF were placed into a testtube and heated under heating conditions shown in Table 12. Then,8.7×10⁴ CFU of Bacillus subtillis IAM 1249 was inoculated into the testtube, shake culture was carried out at 37° C. for 72 hours, and theturbidity (OD, 660 nm) was then measured. Results are shown in Table 12.

TABLE 12 Heating condition OD⁶⁶⁰ Control with no addition of AF 1.160Control with 1% of AF added and not heated 0.836 After addition of 1% ofAF, Heated at 55° C. for 10 minutes 0.513 Heated at 60° C. for 10minutes 0.437 Heated at 80° C. for 10 minutes 0.355 Heated at 90° C. for10 minutes 0.338

As seen in Table 12, a sample heated at 55° C. for 10 minutes afteraddition of 1% of AF shows an antibacterial power(1.160-0.513)/(1.160-0.836) which is about two times that of the controlwith 1% of AF added and not heated.

Test Example 2 (Influence of Heating on Effect of AF, and PreservationTest for Noodle Soup Series)

40 Grams of a powdery soup stock (produced by Yamaki, Co.) and 200 ml ofcommercially available soy sauce were added to 1,000 ml of water toprepare a noodle soup. Bacteria were inoculated into the noodle soup,and the noodle soup was preserved at 30° C., and then, the number ofliving bacteria was counted. Results are shown in FIGS. 3 and 4. FIG. 3is a curve showing the number of living Bacillus subtillis IAM 1249(which will be simply referred to as B. subtillis hereinafter), and FIG.4 is a curve showing the number of living Escherichia coli NRIC 1023(which will be simply referred to as E. coli hereinafter). In FIGS. 3and 4, A-1 and A′-1 are curves each indicating the number of living B.subtillis or E. colli inoculated into the unsterilized noodle soup. Inthe cases of A-1 and A′-1,1,5-D-anhydrofructose was not added, and P andP′ indicate the number of bacteria initially generated.

A-2 and A′-2 are curves each indicating the number of living B.subtillis or E. colli inoculated into the noodle soup sterilized byheating in hot water at 550° C. for 10 minutes. In the cases of A-2 andA′-2,1,5-D-anhydrofructose was not added, and the numbers of bacteriainitially generated are indicated by Q and Q′, respectively. B-1 andB′-1 are curves each indicating the number of living B. subtillis or E.colli inoculated into the unsterilized noodle soup containing 1% of1,5-D-anhydrofructose added thereto, and the numbers of bacteriainitially generated are indicated by P and P′. B-2 and B′-2 are curveseach showing the number of living B. subtillis or E. colli inoculatedinto the noodle soup which was sterilized by heating and into which1,5-D-anhydrofructose was added after cooling of the noodle soup, andthe numbers of bacteria initially generated are indicated by Q and Q′.B-3 and B′-3 are curves each showing the number of living B. subtillisor E. colli inoculated into the noodle soup sterilized by heating at550° C. for 10 minutes after addition of 1,5-D-anhydrofructose, and thenumbers of bacteria initially generated are indicated by R and R′.

The following facts (1) and (2) can be seen from FIGS. 3 and 4:

(1) The numbers of both living B. subtillis and E. colli were reduced byabout one figure (from Q to R, and from Q′ to R′) by heating afteraddition of 1,5-D-anhydrofructose. From this, it can be seen that1,5-D-anhydrofructose has an effect of enhancing a heat sterilizationeffect against gram-positive and gram-negative bacteria.

(2) In the noodle soup containing 1,5-D-anhydrofructose added thereto,the proliferation of both of the B. subtillis and E. colli wassuppressed (from the comparison of the B-2 with B-3 and the comparisonof the B′-2 with B′-3). From this, it can be seen that when the noodlesoup is heated after addition of 1,5-D-anhydrofructose thereto, theproliferation-suppressing effect is further enhanced against thegram-positive bacteria and also increased against the gram-negativebacteria against which the 1,5-D-anhydrofructose originally has a weakproliferation suppressing effect.

Test Example 3 (Heating Effect Exerted to the Antibacterial Power of AF,and Test for Noodle Soup)

40 Grams of a powdery soup stock (produced by Yamaki, Co.), 200 ml ofcommercially available soy sauce and 2% of AF were added to 1000 ml ofwater. The mixture was aseptically filtered and charged in an amount of100 ml into each of ten polypropylene sacks previously sterilized.Meanwhile, 1 ml of the noodle soup (containing a number of livingbacteria of 3.1×10⁶/ml) deteriorated due to “swelling” caused byLactobacillus casei was charged into each of the above-prepared tensacks, which were then sealed so as air not to be left therein. The tensacks were divided into two groups each consisting of five sacks. One ofthe groups was not heated, and the other group was heated in a hot waterat 55° C. for 10 minutes. Then, both of them were preserved at 30° C.,and the occurrence of “swelling” was observed. Results are shown inTable 13.

TABLE 13 Number of preservation days Group 5 10 15 20 Not heated 4/5 0/5— — Heated 5/5 3/5 1/5 0/5

In Table, denominator shows the total number of sacks, and numeratorshows the number of normal sacks.

It can be seen from Test Examples 1 to 3 that the antibacterial power ofAF increased by the heating, and the noodle soup containing AF addedthereto was difficult to deteriorate, namely, the preservability of theAF-added food was enhanced.

Example 11 (Curry)

7 Parts of beef, 57 parts of vegetables (12 parts of potato, 40 parts ofonion and 5 parts of carrot), 1 part of a curry powder, 6 parts of fattyoil, 0.2 parts of sodium glutamate, 1 part of starch and 40 parts of asoup were mixed together, and the mixture was heated and cooked at 80°C. for 1 hour. The resulting product was a curry containing a somewhatlarger amount of soup and having a low viscosity. The followingoperations were conducted in a clean bench. The curry was subdividedeach in an amount of 95 grams into ten plugged vessels previouslysterilized. The ten vessels were divided into two groups each consistingof five vessels.

A 30% solution of AF subjected to an aseptic filtration was added in anamount of 5 g into each of the vessels in one of the groups. Then, 2×10⁵ nutritious cells of Bacillus subtillis incubated previously wereinoculated into the group, and was mixed uniformly. Five grams of a 30%solution of AF subjected to an aseptic filtration was added into each ofthe vessels in the other group. Then, 2×10⁵ nutritious cells of Bacillussubtillis incubated previously were inoculated into the group, and aftermixing uniformly, heated at 60° C. for 10 minutes and then cooledrapidly. Both of the groups were preserved at 300° C., and thepreservability of them was compared by a sensory evaluation test.Results are shown in Table 14.

TABLE 14 Preservation time 12 24 36 48 60 Not heated 5/5 5/5 0/5 — —Heated 5/5 5/5 5/5 5/5 0/5

In Table, denominator shows the total number of vessels, and numeratorshows the number of normal vessels.

Example 12 (Steamed Bread)

1,000 Parts of a weak flour, 250 parts of a liquid shortening, 1,000parts of a liquid egg, 900 parts of very fine sugar, 100 parts of apowdery cheese, 10 parts of a baking powder, 10 parts of salt, 10 partsof AF, 3 parts of xanthan gum, 10 parts of gliadin and 300 parts of warmwater were thrown as starting materials into a mixer. They were mixedtogether at a medium speed for 5 minutes and fermented for about 2hours. The resulting material was divided into 50 g of blocks, theblocks were placed into a mold and were steamed for 30 minutes.

A group (control) with no addition of AF was made in a similar manner toone described above, except that the amount of warm water was adjustedby correcting the amount of water transferred from AF, and thepreservability of both of the control group and the group of the presentinvention were compared with each other. More specifically, ten sampleswere prepared in each of the groups and preserved at room temperature(20 to 30° C.) and thereafter, the number of days taken till generationof slime was examined. Results are shown in Table 15.

TABLE 15 Number of days 1 2 3 4 5 6 Example 12 10/10 10/10 10/10 9/105/10 0/10 Control 10/10 10/10  9/10 0/10 — —

In Table, denominator shows the total number of samples, and numeratorshows the number of normal samples

Example 13 (Kneaded Bean Jam)

30 Parts of powder bean jam, 40 parts of sugar, 1 part of AF, 130 partsof water were mixed together to make a kneaded bean jam. The mixture wasboiled down, so that the initial weight was reduced to one fourth(Example 13). A group (control) with no addition of AF thereto, too, wasmade in a similar manner to one described above, except that the amountof warm water was adjusted by correcting the amount of water transferredfrom AF. Each of the control group and the group of the presentinvention was filled into a plastic cup, and the preservation effects ofboth of the groups were compared at the temperature of 30° C. Resultsare shown in Table 16. The unit in Table 16 is a number of livingbacteria, mold and yeast per gram.

TABLE 16 Number of preservation days 0 1 2 3 4 5 Ex. Number 1 × 10 7 ×10 1 × 10³ 5 × 10⁴ 6 × 10⁵ 8 × 10⁶ 13 of com- mon living bacteria Number10> 10> 4 × 10² 1 × 10² 1 × 10³ 1 × 10⁴ of mold and yeast Con- Number 1× 10 3 × 10³ 1 × 10⁵ 10⁷< — — trol of com- mon living bacteria Number10> 2 × 10³ 4 × 10⁴ 7 × 10⁵ — — of mold and yeast Ex.: Example

Example 14 (Boiled Rice)

900 Grams of rice was washed with water, and 1,080 ml of water and 2.25g of AF (0.25% based on the rice) were added to the rice. The resultingrice mixture was cooked using an 1.8-liter electric rice-cooker (Example14). On the other hand, a boiled rice (a control) was produced in asimilar manner to one described above, except that AF was not added, andthe amount of water transferred from AF was corrected similarly, and thepreservability of the boiled rice of the example 14 and of the controlwere compared with each other. That is, each of the boiled rice wastransferred into a rice tub and preserved at room temperature (18 to 30°C.), and times taken till generation of an acid smell were compared. Theresults showed that 50 hours was taken for the boiled rice in theexample 14, and 20 hours was taken for the boiled rice in the control.The boiled rice in the example 14 at the time when it was transferredinto the rice tub has no problem even in respect of flavor.

Example 15 (Boiled Bean)

Heat-resistant spore forming bacteria were inoculated in the proportionof 10³/gram into a mixture of 100 parts of a sugar solution having aBrix 55 and 2 parts of AF added to 100 parts of steamed kidney beans.The resulting material was heated at 80° C. for 1 hour and then left tostand at 50° C. for 15 hours. Then, the material was drained, sacked,sealed and subjected to a heat sterilization at 100° C. for 40 minutes(Example 15). A group (control) with no addition of AF thereto was madein a similar manner described above, except that the amount of watertransferred from AF was corrected. The products in the Example 15 and inthe control were preserved at 300° C., and the preservability of both ofthem were compared with each other by counting the number ofheat-resistant spore forming bacteria per gram. Results are shown inTable 17. To count the number of heat-resistant spore forming bacteria,each of the products was heated at 95° C. for 10 minutes to killbacteria other than the spore bearing bacteria and then cultured in astandard agar culture medium at 30° C. for 48 hours. The number ofcolonies generated as a result of the culturing was taken as the numberof heat-resistant spore forming bacteria.

TABLE 17 pH of Number of preservation days Product 1 2 3 4 Ex. 15 6.4 5× 10² 7 × 10² 2 × 10³ 4 × 10³ Control 6.4 6 × 10³ 7 × 10⁵ 1 × 10⁷ —(putrefied) Ex.: Example

Example 16 (Flour Paste)

20 Grams of corn starch, 35 grams of a weak flour, 30 grams of a skimmilk powder, 20 grams of a powdered milk, 150 grams of margarine, 250grams of sugar, 3 grams of xanthan gum, 10 grams of AF and 492 grams ofwater were mixed together in a total amount of 1,020 grams to prepare aflour paste. The flour paste was boiled down, so that 10% by weightbased on the total amount was reduced (Example 16). A group (control)with no addition of AF thereto was made in a similar manner describedabove, except that the amount of water transferred from AF wascorrected. The products in the Example 16 and in the control werepreserved at 20° C., and the preservability of both of the products werecompared with each other by counting the numbers of living bacteria pergram after the preservation. Results are shown in Table 18.

TABLE 18 pH of Number of preservation days Product 1 2 3 4 5 6 7 Ex. 166.35 3 × 10 1 × 10² 4 × 10³ 5 × 10³ 4 × 10⁴ 7 × 10⁵ 9 × 10⁸ (Putrefied)Control 6.30 1 × 10³ 6 × 10³ 5 × 10⁵ 9 × 10⁶ — — — (Putrefied) Ex. :Example

Example 17 (Boiled Fish Paste called “Kamaboko”)

30 Grams of salt was added to 1 kg of frozen ground meat of walleyepollack, and the resulting ground fish meat was mashed with itstemperature being maintained at 10° C. or lower for 25 minutes. Fiveminutes before the completion of the mashing, 50 g of white potatostarch, 5 g of AF, 80 g of sugar and 300 g of ice water were added. Theground fish meat after the completion of the mashing was placed into apolyvinylidene chloride film having a diameter of 60 mm and a length of250 mm, and the film was fastened and left to stand for 90 minutes in aconstant-temperature vessel at 40° C. Thereafter, the material in thefilm was heated for 40 minutes in a warm bath having a temperature of85° C. and then cooled immediately with cold water, so that thetemperature of a central portion of a product was equal to or lower than30° C., thus producing a boiled fish paste (Example 17). Meanwhile, aboiled fish paste (a control) was made in a similar manner, except thatthe amount of water transferred from AF was corrected without additionof AF, and the preservability and qualities of the pastes in the Example17 and in the control were compared with each other. That is, theevaluation of the preservability was carried out by leaving the boiledfish paste to stand in a constant-temperature vessel at 30° C., andobserving the presence or absence of the putrefaction and discoloration.The results showed that in the boiled fish paste in the Example 17, thesymptom of the putrefaction appeared slightly after lapse of 12 days andthe discoloration was observed after lapse of 15 days, whereas in thecontrol, the putrefaction was observed after lapse of 7 days and thediscoloration was observed after lapse of 9 days.

Example 18 (Sauce for Grilled Meat)

600 ml of unrefined soy sauce (moromi) was heated, and 2 ml of aceticacid, 140 g of sugar, 100 ml of a sweet sake, 10 g of sodium glutamate,20 g of AF, 10 ml of sesame oil and about 210 ml of water wereincorporated into the unrefined soy sauce. The mixture was agitated andheated to produce a sauce for grilled meat (Example 18). A sauce with noaddition of AF (a control) was made in a similar manner, except that theamount of water transferred from AF was corrected. These sauces werecharged into a small sack and sterilized by hot water at 60° C. for 10minutes, and the preservability of both of the sauces were then comparedat 30° C. Results are shown in Table 19.

TABLE 19 (Unit: number of living bacteria, mold and yeast per gram)Number of days 0 1 2 3 4 5 Ex. Number 1 × 10 7 × 10 1 × 10³ 5 × 10⁴ 6 ×10⁵ 8 × 10⁶ 18 of com- mon living bacteria Number 10> 10> 4 × 10² 1 ×10² 1 × 10³ 1 × 10⁴ of mold and yeast Con- Number 1 × 10 3 × 10³ 1 × 10⁵10⁷< — — trol of com- mon living bacteria Number 10> 2 × 10³ 4 × 10⁴ 7 ×10⁵ — — of mold and yeast Ex.: Example

Example 19 (Kimpira-gobou (Chopped Burdock Root Cooked in Soy and SesameOil))

A flavoring solution having a composition comprising sugar, sweet sakeand soy at a weight ratio of 1:1:4 was added to chopped burdock root ata weight ratio of the burdock root to the flavoring solution of 3:1. Theresulting material was fried for 3 minutes with a medium-power flame toprovide a product of chopped burdock root cooked in soy and sesame oil.The product containing AF added in an amount of 3% based on the totalamount is called an Example 19. A product was produced without additionof AF in a similar manner, except that the amount of water transferredfrom AF was corrected, and this product is called a control. Thepreservability of the products in the Example 19 and in the control at30° C. were compared with each other by counting the numbers of livingbacteria per gram. Results are shown in Table 20.

TABLE 20 pH of Product Flavoring Chopped burdock Number of preservationdays solution root cooked 0 3 8 10 Ex.19 4.8 5.8 <10 2.0 × 10 <10 Mold+Control 4.8 5.8 Foul smell± 2.0 × 10 3.0 × 10 3.4 × 10⁶ Mold++ Foulsmell+ Ex.: Example

Example 20 (Canned Coffee)

A coffee drink was made by blending 1 kg of milk, 300 g of a skim milkpowder, 2 kg of sugar, 600 g of a coffee extract, 15 kg of water and 200g (1%) of AF. When the coffee drink was canned, spores of Bacillusstearothermophilus previously separated and cultured from a coffee drinkcan polluted with flat sour spoilage bacteria were inoculated in anamount of 10³ spores per can into the coffee drink. The resulting coffeedrink was sterilized by heating at 120° C. for 20 minutes in aconventional process (Example 20). A canned coffee drink with noaddition of AF was produced in a similar manner (a control). Then, thetwo canned coffee drinks were preserved in a constant-temperature vesselat 55° C., and the preservability were compared with each other byobserving the occurrence of the deterioration. Results are shown inTable 21. Before the preservation test, the flavor and taste of thecanned coffee in the Example were not different from those in thecontrol, and it was recognized that there was no adverse influence dueto the addition of AF.

TABLE 21 Number of preservation days 5 10 20 30 Ex.20 10/10 10/10 10/1010/10 Control  6/10  0/10 — — Ex.: Example

Numerator shows the number of normal cans, and denominator shows thetotal number of cans

Examples 21 and 22 (Potato Salad)

657 Grams of boiled potato, 50 grams of onion, 100 grams of boiledcarrot, 100 grams of cucumber, 10 grams of common slat and 83 grams ofmayonnaise were mixed well together to produce a potato salad. A saladmade by mixing 15 grams of AF-090 with mayonnaise is called an Example21; a salad made by mixing 15 grams of AF-000 with mayonnaise is calledan Example 22, and a salad made with no addition of AF and with theamount of water transferred from AF-090 being corrected is called acontrol. These salads were placed into lidded containers and preservedat 20° C., and preservability of them were compared by counting themicroorganisms and examining the appearances during the preservation.Results are shown in Table 22. The produced potato salads had a pH valueof 5.3.

TABLE 22 (Unit: number of living bacteria, mold and yeast per gram)Number of preservation days 0 1 2 3 4 5 Ex.21 Number of living 5.7 × 10²1.6 × 10³ 9.3 × 10³ 4.7 × 10⁴ 9.1 × 10⁴ 9.2 × 10⁵ common bacteria Numberof mold 1.0 × 10² 6.1 × 10² 9.8 × 10² 2.3 × 10³ 8.4 × 10³ 6.2 × 10⁴ andyeast Appearance — — — — − — Control Number of living 2.1 × 10³ 2.2 ×10⁴ 3.9 × 10⁶ 2.0 × 10⁷ − — common bacteria Number of mold 1.2 × 10² 1.0× 10³ 3.5 × 10⁴ 1.4 × 10⁶ − — and yeast Appearance — — — Mold and ++ —putrefaction+ Ex.22 Number of living 1.1 × 10³ 4.5 × 10³ 1.9 × 10⁴ 4.4 ×10⁵ 6.4 × 10⁶ — common bacteria Number of mold 1.2 × 10² 1.5 × 10² 1.0 ×10⁴ 5.4 × 10⁵ 8.1 × 10⁶ — and yeast Appearance — — — — — Mold+ Ex.:Example

Examples 23 and 24 (Cut Vegetables)

Commercially available fresh cut vegetables (lettuce and cabbage) for asalad were soaked in two test solutions for 30 minutes and then slightlywashed with water for 30 seconds. After these vegetables were drained,they were preserved at 10° C. for 24 hours, and the numbers of bacteriawas counted. One test solutions (Example 23) contained 3% heat-treatedAF-090, the other solution (Example 24) contained 3% AF-000 were used assoaking solutions, and the control solution contained only water.Results are shown in Table 23. It was observed by naked eyes that adifference in freshness appeared largely between the Examples and thecontrol more than a difference between numbers of living bacteria.

TABLE 23 Before After Item soakage 24 hours Ex.23 Number of commonliving bacteria per 4.0 × 10⁵ 8.1 × 10⁵ gram Number of colon bacilli pergram 2.0 × 10³ 3.5 × 10² pH 6.7 6.4 Ex.24 Number of common livingbacteria per 3.4 × 10⁵ 3.1 × 10⁶ gram Number of colon bacilli per gram1.8 × 10³ 8.6 × 10³ pH 6.7 6.5 Control Number of common living bacteriaper 4.3 × 10⁵ 9.8 × 10⁶ gram Number of colon bacilli per gram 3.5 × 10³4.2 × 10⁴ pH 6.7 6.5 Ex.: Example

Examples 25 and 26 (Ingredient-Containing Boiled Rice)

900 grams of rice was washed with water, and 1,080 ml of water,ingredients for edible wild plant-containing boiled rice (for fourservings, a product of Nagatanien, Co.) and 2.25 grams (in a proportionof 0.25% to the rice) of AF-120 were added to the washed rice. Theresulting rice material was boiled in a 1.8 liter electric rice-cooker(Example 25). On the other hand, an ingredient-containing boiled ricewas produced without addition of AF-120 in a similar manner describedabove, except that the amount of water transferred from AF-120 wascorrected (a control), and an ingredient-containing boiled rice wasproduced with the same amount of AF-000 added in a similar manner(Example 26). The preservability of the three products were comparedwith one another. That is, each of the boiled rice products weretransferred into rice tubs and preserved at room temperature (24 to 32°C.), and the times taken till the generation of acid smell werecompared. As a result, in the boiled rice in the Example 25, 36 hourswere taken; in the control, 16 hours were taken; and in the Example 26,24 hours were taken. The boiled rice in the Example 25 at the time whenit was transferred into the rice tub had no problem even in respect offlavor.

Examples 27 and 28 (Pork Sausage)

5 Grams of a spice was added to 1,000 grams of a minced meat of pork,and they were mixed together for 2 minutes in a mashing machine. Then,20 grams of a natural flavoring containing 50% of common salt was addedto the mixture, and the resulting mixture was mashed for 2 minutes.Further, 80 grams of starch, 20 grams of soybean oil, 40 grams ofalbumen, 20 grams of AF-120 and 120 grams of broken ice and water wereadded, and the mixture was smashed for 2 minutes. The resulting kneadedmeat material was stuffed into a sheep intestine as a stuffer having adiameter of 14 to 22 mm and tied up at a length of about 10 cm.Subsequently, the material was heated for 15 minutes in warm waterhaving a temperature of 70° C. and then left to stand, thereby producinga pork sausage (Example 27). On the other hand, a pork sausage wasproduced in a similar manner, except that the AF-120 was replaced byAF-000 (Example 28). Both of the pork sausages were preserved at 15° C.,and the preservability thereof were compared by examining the pH value,the number of living bacteria per gram and the appearance. Results areshown in Table 24.

TABLE 24 Number of preservation days Item 1 7 9 12 Ex.27 pH 6.37 6.336.42 6.33 Number of living <10 1.5 × 10² 2.5 × 10³ 5.4 × 10⁴ commonbacteria Appearance — — — — Ex.28 pH 6.48 6.45 6.45 6.54 Number ofliving <10 6.4 × 10³ 5.1 × 10⁵ 2.0 × 10⁷ common bacteria Appearance — —— Softened, and smelling of putrefaction Ex.: Example

Examples 29 and 30 (Fried Egg)

400 Grams of a raw egg liquid, 88 grams of a soup stock, 2 grams ofcommon slat, 22 grams of sugar and 7.8 grams of AF-090 were agitated andmixed sufficiently in a homogenizer. The mixture was fried using anfrying pan to produce a fried egg (Example 29). A fried egg was producedin a similar manner, except that AF-090 was replaced by AF-000 (Example30). Both of the fried eggs were preserved at 30° C., and thepreservability thereof was compared. Results are shown in Table 25.

TABLE 25 Preservation time (hr) Item 24 48 Ex.29 Number of living commonbacteria per <10 3.1 × 10⁵ gram pH 7.2 6.3 Ex.30 Number of living commonbacteria per 6.7 × 10² 5.1 × 10⁶ gram pH 6.7 — Ex.: Example

Examples 31, 32, 33 and 34 (Pickled Radish Called “Takuan”)

A roughly pickled radish (containing 7.0% of salt) was desalted and thensacked to produce a flavored pickled radish. In this case, AF was addedin a process described in the Notes given below, and four combinations(Examples 31 to 34) were made as test divisions, as described in Table26 and preserved at 20° C. The number of preservation days was examinedby observing the turbidity of the liquid of the pickled radish, theswelling of the sack and the like. Results are shown in Table 26.

TABLE 26 Number of Addition of At the time of At the time ofpreservation AF desalting flavoring days Ex.31 Not added 0.1% of AF-000 5 days Ex.32 Not added 0.1% of AF-055  8 days Ex.33 0.1% of AF-000 0.1%of AF-000  9 days Ex.34 0.1% of AF-055 0.1% of AF-055 18 days Ex.:Example Notes) 1. The pH value of radish was 6.5, and the pH value ofthe flavoring solution was 5.0 2. Addition of AF at the time ofdesalting Ratio of the weight of pickled radish to the weight of water =1:3 AF-055 was added in an amount of 0.1% based on the total weight ofthe solid and liquid. Left to stand at 5° C. for 24 hours. 3. Additionof AF at the time of flavoring Ratio of the pickled radish to theflavoring solution = 7:3 (by weight) AF-005 was added in an amount of0.1% based on the total weight of the solid and liquid. Sacked and thenheated at 60° C. for 10 minutes.

Examples 35 and 36 (Fruit Juices)

VF strains of Alicyclobacillus acidoterrestris previously cultured wereadded to a juice product made by adding 0.5% of AF-090 and water to aconcentrated grape fruit juice and adjusted to a Brix degree of 11, sothat a concentration of 10³/ml in terms of bacteria in the fruit juicewas obtained (Example 35). An orange juice was also produced in asimilar manner (Example 36). These juices were preserved at 30° C. for21 days. Further, a juice was made as a control without addition of AF.The states of the juices preserved were evaluated, and the state of thejuice preserved, in which a foul taste, a foul smell and the turbidityof the liquid were not detected at all, was taken as “−”, Results areshown in Table 27.

TABLE 27 Brix Preservation Example Fruit juice pH degree AF-090 stateEx.35 Grape fruit juice 3.1 11.0 0.5% − Ex.36 Orange juice 3.5 11.2 0.5%− Control Grape fruit juice 3.1 11.0 — + Orange juice 3.5 11.2 — + Ex.:Example

The growing state of the VF strains cultured at 35° C. for 5 days in aK-culturing medium was confirmed. The K-culturing medium (pH 3.7) hasthe following composition:

2.5 grams of yeast extract, 5.0 grams of peptone, 1.0 gram of glucose,1.0 gram of Tween 80, 15 grams of agar and 990 ml of deionized water;and the medium was adjusted to a pH value of 3.7 with a 25% solution ofmalic acid.

What is claimed is:
 1. A process for producing a food having excellent preservability, comprising the step of heating a food while adding 1,5-D-anhydrofructose to a food, or the steps of adding 1,5-D-anhydrofructose to a food and then heating the food, wherein 1,5-D-anhydrofructose is added in the proportion of 0.01 to 10% by weight based on the food and the heating is carried out at a temperature of 50 to 250° C. and for a time of 1 second to 300 minutes.
 2. A process for producing a food having excellent preservability, comprising the step of heating a food while adding 1,5-D-anhydrofructose previously subjected to a heat treatment to a food, or the steps of adding 1,5-D-anhydrofructose previously subjected to a heat treatment to a food and then heating the food, wherein 1,5-D-anhydrofructose previously subjected to a heat treatment is added in the proportion of 0.01 to 10% by weight based on the food and the heating is carried out at a temperature of 50 to 250° C. and for a time of 1 second to 300 minutes.
 3. The process according to claim 2, wherein heating conditions for the 1,5-D-anhydrofructose previously subjected to the heat treatment are a temperature of 50 to 150° C. and a time of 1 second to 100 hours.
 4. A process for producing a food having excellent preservability, comprising the step of heating a food while adding a food preservative comprising: (a) one or both of 1,5-D-anhydrofructose and 1,5-D-anhydrofructose previously subjected to a heat treatment, and (b) a substance capable of being used as a food additive and having an antibacterial activity to a food, or the steps of adding said food preservative to a food and then heating the food, wherein the proportion of the component (a) in the food preservative is 0.01 to 10% by weight based on the food and the heating is carried out at a temperature of 50 to 250° C. and for a time of 1 second to 300 minutes.
 5. The process according to claim 4, wherein heating conditions for the 1,5-D-anhydrofructose previously subjected to the heat treatment are a temperature of 50 to 150° C. and a time of 1 second to 100 hours.
 6. The process according to claim 4, wherein the substance capable of being used as a food additive and having an antibacterial activity is selected from the group consisting of amino acids; glycerin lower fatty acid esters; sugar esters; salts of vitamin B1; polyphosphates; ethanol; basic proteins and peptides; antibacterial extract from licorice; extract from red pepper; extract from hop; extract from yucca; extract from moso bamboo (thick-stemmed bamboo); extract from grape fruit seed; extract from wasabi (Japanese horseradish) or mustard; acetic acid, lactic acid, fumaric acid and the salts thereof; sorbic acid, benzoic acid and the salts and esters thereof; propionic acid and the salt thereof; chitosan and bacterium DNA.
 7. A method for preserving a food having excellent preservability, comprising the step of heating a food while adding a food preservative comprising: (a) one or both of 1,5-D-anhydrofructose and 1,5-D-anhydrofructose previously subjected to a heat treatment, and (b) a substance capable of being used as a food additive and having an antibacterial activity to a food, or the steps of adding said food preservative to a food and then heating the food, and preserving the resulting food, wherein the proportion of the component (a) in the food preservative is 0.01 to 10% by weight based on the food and the heating is carried out at a temperature of 50 to 250° C. and for a time of 1 second to 300 minutes. 